Flexible magnetic record disks (sometimes called "floppy disks") are increasingly being used as storage devices in computers and other data processing systems. Such disks can be produced very inexpensively compared to the conventional rigid or hard disks, but as a rule their storage capacity is considerably less because of the smaller size and lower track density normally permitted by their nature. Recording on opposite sides of a flexible magnetic record disk is advantageous in order to increase its storage capacity.